Measles Vaccines vs Measles Strains

Most people understand that for every virus or bacteria, their can be multiple strains of the same organism that cause disease.

For example, there is flu A and B, swine flu, bird flu, and even dog flu.

In the case of flu, those different strains are a problem, because having immunity to one, doesn’t mean that you will have immunity to others. In fact, usually you won’t, whether it is natural immunity from a previous infection or immunity from a vaccine.

Pains with Strains

Do we have the same issues with other diseases?

We certainly have situations in which vaccines don’t cover all disease strains, including:

Hib – only covers Haemophilus influenzae type b, which causes invasive disease, like meningitis, pneumonia, and sepsis, but not other Haemophilus influenzae strains that can cause ear infections

Polio – originally protected against three serotypes of polio, but monovalent (one strain) and bivalent (two strains) oral poliovirus vaccines have also been available to respond to outbreaks and bOPV is the one used for routine immunization, except in industrialized, polio-free countries that use the IPV shot

It may come as a surprise to some people, but the whole world doesn’t use the same vaccines. For example, unlike the United States, Japan has used measles vaccines derived from AIK‐C, CAM, and Schwarz strains of the measles virus.

And just how many wild strains of measles are there? It’s hard to know, but consider that a study of 526 suspected measles cases from 15 outbreaks over 3 years in one state of India found at least 38 different strains.

Myths About Measles Strains

Do the measles vaccines cover all of the measles strains that cause outbreaks around the world?

Yes they do, despite the myths you may hear about mutated measles strains.

This came up a lot during the Disneyland measles outbreak, when folks first tried to place blame on a vaccine strain and then on the fact that the outbreak strain didn’t match the vaccine strain.

“…California patients were genotyped; all were measles genotype B3, which has caused a large outbreak recently in the Philippines…”

CDC Measles Outbreak — California, Dec 2014–Feb 2015

And it is coming again in the latest measles outbreak in Minnesota. Could that outbreak be caused by a vaccine strain? Anything is possible, but it’s not. A communication’s director for the Minnesota Department of Health has confirmed that “that the virus strain making people sick in this outbreak is the B3 wild-type virus.”

Of course, none of these outbreaks are started by a vaccine strain of measles shed from someone who was recently vaccinated. It also had nothing to do with the fact that the strains didn’t match – after all we aren’t talking about the flu.

These outbreaks are imported from other countries by folks who typically aren’t vaccinated or are incompletely vaccinated and mostly spread among other people who are unvaccinated.

So what’s the most important thing to understand when considering all of these vaccine strains and wild strains of measles? It is that “there is only 1 serotype for measles, and serum samples from vaccinees neutralize viruses from a wide range of genotypes…”

In other words, the measles vaccine works against all strains of measles in all genotypes of measles. That makes sense too, because the measles virus, unlike influenza, is monotypic.

There is only one main type of measles virus, despite the many small changes in the virus that can help us identify different strains and genotypes. And these changes don’t affect how antibodies protect us against the measles virus.

What To Know About Measles Strains

The best way to get protected against all measles strains is to get vaccinated with two doses of the MMR vaccine.

Ooh hang on, you said “Do the measles vaccines cover all of the measles strains that cause outbreaks around the world? Yes they do”. My problem here is that you wrote measles vaccines plural. So my question to you is simple, does the MMR (most common strain used in US vaccines), provide immunity against ALL measles strains?

Japan is actually one of the only countries that does not vaccinate for Measles. As mentioned they used to use the standard MMR however so many children had severe adverse reactions and disabilities that they banned that vaccine. It is public record that they don’t vaccinate for it. I believe it was banned in 1993 and many times WHO has tried to get them to change their stance on it but the ban remains in place.

It sounds like you are saying that measles outbreaks are not of concern to vaccinated people, since the vaccine is effective on all strains due to the single serotype. Although… if that is the case, why is the vaccine made up of multiple strains? Wouldn’t one be enough?